Toaster

ABSTRACT

A bread toaster comprising a housing and at least one slot opening for receiving an article to be toasted. The bread is progressively traversed by a linear heat source in a pair of passes. A first pass is at a rate which is sufficient to drive moisture from at least the surface of the bread, but which is insufficient to significantly darken the bread. A second pass is at a rate which is sufficient to darken and toast the surface to a desired degree.

BACKGROUND OF THE INVENTION

[0001] This invention relates to toasters and, more particularly, to ahigh speed toaster which will toast bread slices at a rate which istwice as fast as commercially available toasters.

[0002] Conventional toasters typically employ spaced heating elementswhich comprise resister wires mounted on or wrapped about planarinsulating sheets. Other arrangements include coiled resisters mountedby insulators to form a planar zig zag pattern on the sides of the breadto be toasted. The pattern formed by the resistance wires generallycomprises the entire surface area of the bread faces. Reflectors aremounted to direct the radiant heat toward the bread surface.

[0003] Bread is placed in a movable carriage and is manually loweredbetween the planar heating elements against the bias of a spring. Alocking mechanism holds the carriage in this position for apre-selectable period of time until the bread has reached a desireddegree of browness. A bimetallic sensor that deflects from heatactivates a circuit to release the latching trigger and permit thecarriage to move to an upper non toasting position. When the carriage ismoved to the latter position the heating elements are de-energized.

[0004] These prior art toasters tend to dissipate much of the radiantheat energy rather than concentrate such energy on the bread to betoasted. Furthermore, after each cycle the bimetallic latching elementmust cool to a degree which is sufficient to lock the carriage in itsdownward toasting position. These factors contribute to a relativelyslow toasting cycle or series of toasting cycles.

BRIEF SUMMARY OF THE INVENTION

[0005] When used in the following description and claims, the term breadis intended to cover bread slices and a wide variety of likecomestibles, including waffles and bagels.

[0006] This invention provides a toaster having a linear heat sourcewhich scans the surface of the bread in a first pass and at a rate whichis sufficient to drive moisture from at least the surface of the bread,but which is insufficient to significantly darken the surface. Thesurface of the bread is then progressively traversed with the linearheat source in a second pass at a rate which is sufficient to darken andtoast the surface to a desired degree.

[0007] According to one aspect of this invention, the linear heat sourcecomprises a ceramic rod wound with a nichrome resistance wire. Thelinear heat source is provided with a semi cylindrical reflector whichclosely conforms to the heat source to focus the radiant energy on anarrow surface area of the bread to be toasted. A pair of such linearheat sources are mounted parallel to each other and horizontallyadjacent the upper ends of a bread carriage guide. The bread carriage ismounted between the guides and is adapted to lower and raise breadslices mounted thereon between the parallel heat sources. The carriageis reciprocally driven by a chain and sprocket arrangement which isreversibly driven by a dc motor.

[0008] More specifically, this invention comprises a toaster housinghaving at least one slot opening to receive the bread to be toasted. Aholding carriage is movable relative to the slot opening between a firstposition adjacent the opening to a second position spaced from theopening. A drive motor drives the carriage through a chain drivetransmission and moves the carriage from the first position to thesecond position and from the second position back to the first position.A first switch is responsive to movement of the carriage to the secondposition to reverse the travel of the carriage from the second positionto the first position. A second switch is responsive to movement of thecarriage to the first position to de-energize the motor and terminatecarriage travel. A substantially linear heat source is adjacent thefirst position and extends transversely across the path of travel of thecarriage so that the bread passes the linear heat source as the carriagetravels from the first position to the second position, and again passesthe linear heat source as the carriage moves from the second positionback to the first position.

[0009] According to another aspect of this invention the toasterincludes a conventional carriage which is manually operated to a down ortoasting position against the bias of a return spring. The carriage islatched in this position by a solenoid operated latching member. Linearheat sources are mounted in a vertical position on a chain drivencarriage which is driven by a reversing dc motor. With the carriage in adown and latched position, the linear heat sources traverse oppositefaces of the bread in opposite directions in a first pass to drivemoisture from at least the surfaces of the bread and then traverse thesurfaces in an opposite direction in a second pass at a rate which issufficient to darken and toast the surface to a desired degree.

[0010] In each embodiment, opposite sides of the toaster are providedwith transparent glass panels so that the toasting operation may beobserved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of a toaster according to one aspectof this invention;

[0012]FIG. 2 is a perspective fragmentary view of the toasterillustrated in FIG. 1 with the outer casing removed to show details ofconstruction;

[0013]FIG. 2a is a cross sectional view, the plane of the section beingindicated by the line 2-a-2 a in FIG. 2;

[0014]FIGS. 3, 4, and 5 illustrate the circuitry for the toaster;

[0015]FIG. 6 is a perspective view of a toaster according to a furtheraspect of this invention;

[0016]FIG. 7 is a fragmentary view of certain interior structure of thetoaster illustrated in FIG. 6;

[0017]FIG. 8 is a schematic view of certain interior operating structureaccording to another aspect of this invention;

[0018]FIG. 9 is a perspective view of a toaster according to a furtheraspect of this invention; and

[0019]FIG. 10 is a schematic view of certain interior operatingstructure according to another aspect of this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring now to FIGS. 1 and 2 there is illustrated a toaster 10according to one aspect of this invention. The toaster 10 includes ahousing or casing 12 having a top slot opening 14 adapted to receivebread, bagels, waffles, or the like. The sides of the housing 12 areprovided with transparent panels 16 so that one may view the toastingprocedure.

[0021] Referring particularly to FIG. 2 the toaster includes a base 18,a support table 20, a carriage 22, and guide supports 24 and 26 for thecarriage 22. The carriage 22 is provided with a wire cage assembly 28which supports the articles to be toasted on the carriage 22. Thecarriage 22 is provided with axially aligned end projections 30 and 32which respectively extend through slots 34 and 36 in the supports 24 and26. The projections 30 and 32 are guided in the slots by roller elements38 which bare against the supports 24 and 26. The projection 32 isattached at its end to a drive chain 40 which is trained about an upperidler sprocket 42 and a lower drive sprocket 44. The sprocket 44 isdriven by a reversible dc motor 46.

[0022] A pair of linear heat sources 48 and 50 extend transversely tothe path of travel of the carriage 22 and are mounted adjacent the upperends of the supports 24 and 26. Each linear heat source 48 and 50includes a resistance heating coil 52 wound about a ceramic rod 54. In aspecific embodiment of the invention, the ceramic rod is wound with 35turns of N180-012 nichrome wire per six inches of rod. Asemi-cylindrical, highly reflective reflector 56 partially surroundseach rod and wire assembly.

[0023] With the carriage 22 in an up position and with an upper guideroller 38 engaging a normally closed upper limit switch 57, bread slicesare loaded onto the carriage 22. A start cycle push button 58 isdepressed to start a cycle. Initiation of the cycle provides power tothe linear heating elements 48 and 50 to preheat the elements to anoperating temperature. When the operating temperature is reached, thecarriage 22 is lowered and the bread is progressively traversed by thelinear heat sources 48 and 50. The carriage is lowered at a rate whichis sufficient to drive moisture from at least the surface of the bread,but which is insufficient to significantly darken the surface. When thecarriage reaches the lower portion of the travel the lower guard roller38 closes a normally open limit switch 60 to reverse the drive directionof the motor 46 so that the bread is progressively traversed in a secondpass by the linear heat sources 48 and 50. The rate of traversal issufficient to darken and toast the surface to a desired degree.

[0024] Referring now to FIGS. 3, 4, and 5, a control circuit 62 includesrelays CR1, CR2, CR3, and TDLY, respectively having coils 64, 66, 68,and 70 connected in parallel to a first latching circuit 72. The coil 64of the relay CR1 is connected to the first latching circuit 72 through anormally openly contact 74 of the relay TDLY. The first latching circuit72 includes the cycle start push button 58 and the normally closed upperlimit switch 56 connected in parallel to the positive terminal L1 of apower source. The cycle start push button 58 is connected to thepositive terminal L1 through a normally closed contact 75 of the relayCR3, while the upper limit switch 56 is connected to the positiveterminal L1 through a normally open contact 76 of the relay CR1.

[0025] The coil 68 of the relay CR3 is connected to the first latchingcircuit 72 through a second latching circuit 78, which includes anormally open contact 80 of the relay CR3 connected in parallel to thenormally open lower limit switch 60.

[0026] A motor circuit 82 includes a contact arrangement of relay CR3that forms a double-pole, double-throw switch 84 connecting the motor 46to positive and negative terminals of a dc speed control output. Anormally open contact 86 of CR1 is disposed in the motor circuit 82between the switch 84 and the motor 46. In a first position, the switch84 connects the dc speed control output to the motor 46 with a polaritythat causes the motor 46 to rotate in a first direction which drives thecarriage 22 downwardly, whereas in a second position, the switch 84connects the dc speed control output to the motor 46 with a reversepolarity that causes the motor 46 to rotate in a reversed direction thatmoves the carriage upwardly.

[0027] A heater circuit includes the heating coils 52 that are providedwith power through a phase controller 54. The phase controller 54 isconnected to a control signal 56 through a normally open contact 58 ofthe relay CR2.

[0028] When the cycle start push button 58 is depressed to start acycle, the first latching circuit 62 closes through the cycle start pushbutton 58. As a result, the coil 66 of the relay CR2 is energized, whichcloses the contact 58 of the relay CR2 in the heater circuit 88, therebytransmitting the control signal to the phase control 54 and providingpower to the heating coils 52. In addition, the coil 70 of the relayTDLY is energized, which closes the contact 74 of the relay TDLY,thereby providing power to the coil 64 of the relay CR1. Theenergization of the coil 64 of the relay CR1 closes the contact 86 andthe motor circuit 82, thereby providing power to the motor 46 andcausing the carriage 22 to move downwardly. In this manner, there is atime delay between the provision of power to the heating coils 52 andthe motor 46, which permits the heating coils 52 to heat up before thecarriage is moved downwardly past the heating coils 52.

[0029] The energization of the coil 64 of the relay CR1 also closes thecontact 76 in the first latching circuit 62, thereby closing the firstlatching circuit 72 through the upper limit switch 56 and permitting thecycle start push button 58 to be released, without cutting off power tothe coils 64, 66, 68, and 70 of the relays CR1, CR2, CR3, and TDLY. Whenthe carriage reaches the bottom of its downward travel, the lower limitswitch 60 is closed, hereby energizing the coil 68 of the relay CR3,which moves the switch 84 to the second position, closes the switch 80,and opens the switch 74. The movement of the switch 84 to the secondposition connects the dc speed control output to the motor 46 with areverse polarity that causes the motor 46 to rotate in a reverseddirection to move the carriage upwardly past the heating coils 52 for asecond pass. The closing of the switch 80 permits power to be providedto the coil 68 of the relay CR3 when the carriage moves upwardly and thelower limit switch 60 opens. The opening of the switch 75 cuts off powerto the cycle start push button 58, thereby disabling it.

[0030] When the carriage reaches the top of its upward travel, the upperlimit switch 56 opens, which cuts off power to the coils 64, 66, 68, and70 of the relays CR1, CR2, CR3, and TDLY, thereby completing the cycleof operation of the toaster.

[0031] Referring now to FIGS. 6, 7, and 8, there is illustrated atoaster 100 having a housing or casing 110 provided with a breadreceiving opening or slot 112.

[0032] Referring more specifically to FIG. 7 the toaster 100 includes abread receiving carriage 114 which is mounted for reciprocation on guiderods 116 and includes bread retaining wires 118. The carriage 114 isassociated with conventional prior art mechanisms associated withconventional pop up toasters. Such mechanisms include a manuallyoperated slide handle 120 (FIG. 6) which is connected to the carriage114 and which lowers the carriage against the bias of a spring 122. Alocking mechanism, which may be a solenoid operated latch 124, isprovided to retain the carriage 114 in a lowered position during atoasting cycle but which is released at the end of the cycle so that thecarriage is driven upwardly by the spring 122.

[0033] The mechanism illustrated in FIG. 7 performs substantially thesame toasting operation as the mechanism illustrated FIGS. 1 and 2, butthe mechanism shown FIG. 7 employs linear heating elements 126 and 128which are movable relative to the article to be toasted as opposed tomoving the article to be toasted past the stationary heating elements asis shown in FIGS. 1 and 2.

[0034] Furthermore, in the embodiment illustrated in FIG. 7 theoperating circuitry is substantially identical to that illustrated inFIGS. 3 through 6 and will not be described again in detail.

[0035] An endless drive chain 130 is trained about idler sprockets 132,134, and 136 and is driven by a drive sprocket 138. The drive sprocket138 is, in turn, driven by a reversible dc motor 46 a. The linear heatsources 126 and 128 are fixed to the chain for movement therewith andare guided at their lower ends by troughs 140.

[0036] With the carriage 114 in a down and locked position, a cyclestart button 58 a is depressed to initiate a preheat operation similarto the operation described with respect to the embodiment shown in FIGS.1 and 2. At the completion of the preheat portion of the cycle, themotor 46 a drives the chain so that the heating elements 126 and 128 aredriven in opposite directions to traverse the bread surfaces in a firstpass and at a rate which is sufficient to drive moisture from at leastthe surface of the bread, but which is insufficient to significantlydarken the surface. At the completion of the traversal of the heatingelements 126 and 128 in the first direction, as determined by theposition of a normally open limit switch 60 a which corresponds to thelimit switch 60, the limit switch 60 a is closed. When the limit switch60 a is engaged by the heating element 126 the motor 46 a reverses itsdirection and the heating elements 126 and 128 progressively traversethe surface area of the articles to be toasted with a second pass and ata rate which is sufficient to darken and toast the surface to a desireddegree. At the completion of this traversal, the linear heating element126 engages a normally closed limit switch 56 a, which corresponds tothe limit switch 56, to terminate the toasting cycle as previouslydescribed. However, in addition, the solenoid latch 124 releases thecarriage 114 so that it may be driven to an up position by the spring122 to permit removal of the toast from the slot 112.

[0037] Referring now to FIG. 8 there is illustrated, in schematicfashion, an embodiment which is similar to FIG. 7 but which employs analternate mechanism for traversing the heat sources past the breadsurfaces. The conventional bread carriage pop up mechanism is identicalto that illustrated and described with respect to FIG. 7 and is notrepeated in FIG. 8 for purposes of simplicity.

[0038] In FIG. 8, a drive motor 46 b has an output shaft 200 providedwith a pair of spaced drive sprockets 210 and 212. A pair of chains 214and 216 extend between the drive sprockets 210 and 212 and a pair ofidler sprockets. At the completion of the preheat portion of the cycle,the motor 46 b drives the chains 214 and 216 so that heating elements222 and 224 attached to the chains are driven as a spaced parallel unitpast opposite sides of the bread in a first pass. At the completion ofthe traversal of the heating elements in the first direction, asdetermined by the position of a normally open limit switch 60 b whichcorresponds to the limit switch 60, the limit switch 60 b is closed.When the limit switch 60 b is engaged by the heating element 224 themotor 46 b reverses its direction and the heating elements 222 and 224progressively traverse the surface areas of the articles to be toastedwith a second pass. At the completion of this traversal, the linearheating element 224 engages a normally closed limit switch 56 b, whichcorresponds to the limit switch 56, to terminate the toasting operation.

[0039] Referring now to FIGS. 9 and 10, there is illustrated a toaster300 according to a still further aspect of this invention. The toaster300 includes a base 310 and transparent side panels 312 and 314. Thetoaster 300 has open ends for the insertion and discharge of articles tobe toasted. A heating element housing 316 is provided in the mid portionof the side panels 312 and 314 and enclose a pair of linear heatingelements 318 and 320 on each side of the toaster 300.

[0040] As may be seen in FIG. 10, a bread conveying belt 322 receivesbread at one end of the toaster 300 for conveyance in the direction ofthe arrow 324. The belt 322 may be a wire mesh having perforated drivetracks 326 at its lateral edges. The drive tracks 326 engage an idlersprocket roll 328 and the belt is driven by a drive sprocket roll 330.The drive sprocket roll is, in turn, driven by a dc drive motor 46 c.

[0041] In a toasting cycle, the bread is driven by the conveyor belt 322past the linear heating elements 318 and 320. A first one of theelements 318 and 320 serves to drive out the moisture and the second oneof the elements serves to darken the bread in the manner previouslydiscussed.

[0042] The control circuit for the toaster 300 is similar to the circuitillustrated in FIGS. 3, 4, and 5, but, since the bread is conveyed in asingle direction past paired heating elements, a reversing circuit forthe motor 46 c is not needed. A single limit switch 56 c, correspondingto the limit switch 56 in FIG. 3 is provided to shut off the motor 56 cat the end of the cycle. To this end, there is provided a cam button 332on the track 326 which engages the switch 56 c. The preheat circuit isprovided, as is a start switch 58 c. The bread is loaded onto the belt322 at the completion of the preheat cycle which, of course, isindicated by movement of the belt 322.

What is claimed:
 1. A bread toaster comprising a toaster housing, atleast one slot opening in said housing adapted to receive an article tobe toasted, a holding carriage moveable relative to said slot openingbetween a first position adjacent said opening to a second positionspaced from said opening, a drive motor for said carriage, a drivetransmission between said carriage and said motor adapted to move saidcarriage from said first position to said second position and from saidsecond position back to said first position, a start switch adapted toenergize said motor in a first drive direction, a first switchresponsive to movement of said carriage to said second position toreverse the drive direction of said motor and the direction of travel ofsaid carriage from said second position to said first position, a secondswitch responsive to movement of said carriage to said first position tode-energize said motor and terminate carriage travel, a substantiallylinear heat source adjacent said first position and extendingtransversely across the path of travel of the carriage.
 2. A breadtoaster according to claim 1 wherein said start switch energizes saidlinear heat source for a predetermined period of time sufficient topreheat said source, and energizes a time delay relay which, in turnenergizes said motor at the completion of said predetermined period oftime.
 3. A bread toaster according to claim 1 wherein a pair of linearheat sources are provided to heat opposite sides of said bread.
 4. Abread toaster according to claim 1 wherein said heat source comprises aceramic rod wound with a resistance heating element.
 5. A bread toasteraccording to claim 1 wherein said housing has opposite transparentsidewalls which permit viewing of the surfaces being toasted.
 6. A breadtoaster comprising a toaster housing, at least one slot opening in saidhousing adapted to receive an article to be toasted, a holding carriagemovable relative to said slot opening between a first position adjacentsaid opening to a second position spaced from said opening, a linearheat source mounted for movement relative to a surface of said article,a drive transmission between said heat source and a drive motor adaptedto drive said heat source from one end of said surface to an oppositeend of said surface upon energization of said motor in a first drivedirection and adapted to drive said heat source from the opposite end ofsaid surface to said one end of said surface upon energization of saidmotor in a second direction, a start switch adapted to energize saidmotor in its first drive direction, a first switch responsive to travelof said heat source to said opposite end of said surface to energizesaid motor in said second direction, and a second switch responsive totravel of said heat source to said one end of said surface tode-energize said motor.
 7. A bread toaster according to claim 6 whereinsaid start switch energizes said linear heat source for a predeterminedperiod of time sufficient to preheat said source, and energizes a timedelay relay which, in turn, energizes said motor at the completion ofsaid predetermined period of time.
 8. A bread toaster according to claim6 wherein a pair of linear heat sources are provided and each heatsource is adapted to traverse a surface of said article to be toasted.9. A bread toaster according to claim 6 wherein each heat source travelsin a direction opposite the other heat source.
 10. A bread toasteraccording to claim 6 wherein each heat source travels in the samedirection.
 11. A bread toaster according to claim 6 wherein said heatsource comprises a ceramic rod wound with a resistance heating element.12. A bread toaster according to claim 6 wherein said housing hasopposite transparent sidewalls which permit viewing of the surfacesbeing toasted.
 13. A method of toasting bread comprising the steps ofprogressively traversing a surface area of the bread with a linear heatsource in a first pass and at a rate which is sufficient to drivemoisture from at least the surface of the bread, but which isinsufficient to significantly darken said surface, and progressivelytraversing said surface area of the bread with a linear heat source in asecond pass at a rate which is sufficient to darken and toast saidsurface to a desired degree.
 14. A method according to claim 13 whereinsaid linear heat source comprises a pair of parallel heat elements andwherein the bread is conveyed between said heat elements.
 15. A methodaccording to claim 13 including the step of preheating said linear heatsource prior to the step of traversing said surface area.
 16. A methodaccording to claim 13 wherein said first and second passes are inopposite directions.
 17. A method according to claim 13 wherein thebread is stationary and wherein said heat source moves to progressivelytraverse the surface of the bread.
 18. A method of toasting breadcomprising the steps of conveying said bread between a first pair oflinear heat sources at a rate which is sufficient to drive moisture fromat least the surface of the bread, but which is insufficient tosignificantly darken said surface, and conveying said bread between asecond pair of linear heat sources at a rate which is sufficient todarken said surface to a desired degree.
 19. A method according to claim18 including the step of preheating said linear heat sources prior toconveying the bread between said first pair of linear heat sources.